1. Field of the Invention
This invention generally relates to apparatus and methods for packaging articles. The invention specifically relates to apparatus and methods for attaching pre-printed promotional banners, coupons and similar items to the exterior of a flexible snack food package.
2. Description of the Background Art
It has long been recognized as desirable to attach promotional banners, advertising coupons, "premiums" or similar items to bags or other packages of commercial products. One of the simplest methods employed is to print a coupon directly onto the bag or package as part of its labelling. The inconvenience of tearing or cutting the package to separate the coupon is apparent, and consumers do not favor this approach. Of course, cutting or tearing the package destroys its integrity, so that the coupon cannot readily be removed until the package is empty.
Another method for providing a coupon on the exterior of a package is to attach the coupon with an adhesive to the package. Typically, coupons are printed upon pressure-sensitive label stock, and are adhered to the web of packaging material one label at a time as the packaging material is being processed to form a package. Preparing and affixing such coupons has shown to be relatively expensive, however.
One potentially inexpensive method for providing a coupon on a flexible package employs a continuous banner stock. The text of coupons or other promotional materials are printed upon the banner stock, which is fed in tandem with the packaging stock to a form-fill-seal apparatus. The banner stock is affixed to the packaging material at the same time the top and bottom seals are formed. In general the banner stock is relatively inexpensive, and appropriate vertical form-fill-seal equipment requires only minor modification to accommodate it.
A specific example of this method for providing a coupon on the exterior of a package is illustrated in U.S. Pat. No. 2,815,620 to Prodigo. Prodigo discloses a conventional vertical form, fill and seal apparatus for packaging products wherein a web of packaging material is fed to a vertical tube, formed into a tubular package preform and sealed. Prodigo advances his tubular preform with clamping jaws which pull the preform down along the vertical tube in increments equal to the length of the finished package. The clamping jaws also form the transverse seal of the package and sever the sealed package from the preform.
The Prodigo patent illustrates a method for providing a detachable coupon to the exterior of the package. Banner stock is fed into proximity of the package preform well after the preform has been formed around a former tube and longitudinally sealed, however. This feature is seen in FIG. 3 of the Prodigo patent. The banner web and packaging film are not united until the clamping jaws adhere the banner web to the package preform at the location of the transverse package seals.
It has been found, however, that the tension of the banner stock can interfere with the desired smooth transport of the packaging material in apparatus employing means other than clamping jaws to advance the preform. Pull belts and pulleys, such as those disclosed in U.S. Pat. No. 4,288,965 to James, are in common use in vertical form-fill-seal apparatus. Generally, the pull belts engage the side edges of the preform and then advance the preform down along the form-fill tube in package-length increments. When banner stock is fed into joinable proximity to a preform, i.e., as Prodigo has done, the continuous banner unacceptably interferes with the advance sequence of the preform. As a result, a large amount of the banner stock can be lost as waste. Tracking and registration problems can also be caused by improper tension on the banner rollstock.